Application of a near coincidence site lattice theory to the orientations of YBa2Cu3O7-x grains on (001) MgO substrates
Hwang, D.M., T.S. Ravi, Ramamoorthy Ramesh, S.-W. Chan, C.Y. Chen, L. Nazar, X.D. Wu, A. Inam, T. Venkatesan
Various orientations of YBa2Cu3O7-x grains in polycrystalline films prepared on (001)MgO substrates by in situ laser deposition were determined using electron diffraction. Eight different types of in-plane orientations have been observed. These orientations agree well with the prediction of a simplified theory of near coincidence site lattice between YBa2Cu3O7-x and MgO. The YBa2Cu 3O7-x grains were found to have a high probability of forming low angle or low Σ boundaries among themselves. These grain boundaries are of low energy and should exhibit a high connectivity of Cu-O-Cu chains. Therefore, YBa2Cu3O7-x thin films on MgO can attain a Tc of ∼90 K and a Jc of ∼10 6 A/cm2 at 77 K.
Applied Physics Letters
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